Klawansky S, Yeung A, Berkey C, Shah N, Phan H, Chalmers TC., Department of Health Policy and Management, Harvard School of Public Health, Boston, Massachusetts 02115, USA. Meta-analysis of randomized controlled trials of cranial electrostimulation. Efficacy in treating selected psychological and physiological conditions. J Nerv Ment Dis. 1997 Dec; 185 (12): 766-7
Researchers conducted an extensive literature review of cranial electrostimulation (CES) efficacy that identified 18 of the most carefully conducted randomized controlled trials of CES versus sham treatment.
For the 14 trials that had sufficient data, the techniques of meta-analysis was used to pool the published results of treating each of four conditions: anxiety (eight trials), brain dysfunction (two trials), headache (two trials), and insomnia (two trials).
Because studies utilized different outcome measures, an effect size method was employed to normalize measures which were then pooled across studies within each condition. The meta-analysis of anxiety showed CES to be significantly more effective than sham treatment (p < .05).